Biofilm-related characteristics in clinical isolates of Extraintestinal Pathogenic E. coli

Abstract

The rapid increase in antibiotic resistance is one of the leading global health issues at present time. Bacteria’s resistance to antibiotic agents can be a thousand times higher when they are embedded in an extracellular biopolymer matrix, defined as biofilm. The biofilm state is a major driver of persistent infections, offering a challenge in providing adequate treatment. Biofilm producing E. coli is a common cause of infections at extraintestinal sites, like the urinary tract or the bloodstream. By investigating the biofilm phenotype of clinical ExPEC isolates and correlating it to other phenotypic and genotypic traits, we aim to generate novel knowledge in this field, and contribute to predict the clinical manifestation, severity, and treatment of such infections.

The biofilm forming capacity of the strains was evaluated both qualitatively and quantitatively. The presence of major biofilm matrix components, curli and cellulose, was investigated by staining with Congo Red and Calcofluor. Additional quantitative measures of number of CFUs contributing to the biofilm, total biomass on pegs and in wells were conducted. Genotypic characterization of the strains ST, fimH/fumC allele, serotype, plasmids, virulence factors and resistance genes were conducted by uploading the strains genome to specific webtools. Additionally, the strains motile and haemolytic behaviour was investigated. These traits were analysed for correlation to their biofilm phenotype.

Our results display preliminary trends within biofilm formation in clinical ExPEC isolates, with a potential for further investigation. We suggest that complementation of genotypic analyses and effects of knock out mutants is further investigated with a bigger sample size, to better understand the effects these traits exhibit on biofilm formation.